There are, of course, two sides to any transaction, the merchant and the customer. Pushing costs to one side or the other is another way to innovate. Take Bluebird, the payment card from American Express ( AXP) and Wal-Mart ( WMT), which I wrote about here last month. As MoneyMorning notes , customers aren't being charged for using the cards when they put their paychecks into them and using Wal-Mart cashiers or AmEx ATMs to take the money out. Instead, Bluebird is charging merchants high interchange fees. Each mobile payment app that appears -- and Mobile Payments Today recently profiled six of them gets a chance to rewrite the rules. There is a "Wild West" quality to the market now, but that just means competition. And if you don't think the current players aren't hip to that, you're mistaken. How would you like a credit card with a keypad on it that makes online payments more secure and cheaper? MasterCard is testing one, says CNET. Watch your mailbox. At the time of publication, the author was long GOOG and MSFT.Follow @DanaBlankenhornThis article is commentary by an independent contributor, separate from TheStreet's regular news coverage.